1. Field of the Invention
The present invention relates to a straddle-type vehicle.
2. Description of the Related Art
Japanese Patent No. 4627389 discloses a technique for mounting a vehicle body vibration control damper so as to extend between predetermined positions on a vehicle body frame of a four-wheeled vehicle employing an independent suspension. When the wheels receive a reaction force from the ground surface while the vehicle is running, each wheel independently transmits a reaction force subjected to damping by a suspension device for the wheel to the vehicle body frame.
In a snowmobile, a track belt that transmits a driving force to the ground surface has a predetermined dimension in the vehicle width direction. A suspension that suspends this track belt uses a plurality of links provided between a vehicle body frame and the track belt. Suspension by the plurality of links allows the track belt to swing up and down around a virtual axis extending in the vehicle width direction relative to the vehicle body frame as a center (the position of the virtual axis always varies, rather than staying at one position).
Meanwhile, in an ATV (All-Terrain Vehicle), a pair of drive wheels that transmit a driving force to the ground surface are spaced apart from each other in the vehicle width direction. A suspension that suspends the drive wheels includes a rear arm in which one end is supported by the vehicle body frame via an axle provided on the vehicle body frame and extending in the vehicle width direction, and the other end of which rotatably supports a pair of drive wheels. The rear arm is arranged to swing up and down around the axle extending in the vehicle width direction relative to the vehicle body frame as a center.
There may be a case, when a vehicle runs, in which ground touching portions spaced apart from each other in the vehicle width direction may respectively receive reaction forces from the ground surface that are mutually different in the magnitude. In such a case, in a straddle-type vehicle, such as a snowmobile, an ATV, or the like, a moment that pushes up one side of the axle extending in the vehicle width direction may be transmitted to the vehicle body frame due to the arrangement of the suspension described above, wherein this moment is not caused in a conventional four-wheeled vehicle. This may cause unique vibrations to be generated in the vehicle body frame.